How could anyone be with Christ in paradise that day? Christ didn't ascend himself that day. it was several days later, no? Seems the WT comma placement explination makes sense.
Where was this paradise then? You are correct, Jesus did not ascend into heaven until after the resurrection so the "paradise" Jesus was talking about could not have been heaven at that time.
With Christ in Paradise
And Jesus said to him, “Assuredly, I say to you, today you will be with Me in Paradise.” ~Luke 23:43
He first descended
But to each one of us grace was given according to the measure of Christ’s gift. Therefore He says:
“When He ascended on high,
He led captivity captive,
And gave gifts to men.”
(Now this, “He ascended”—what does it mean but that He also first descended into the lower parts of the earth? He who descended is also the One who ascended far above all the heavens, that He might fill all things.) ~Eph 4:7-10
Abraham’s bosom (incorrectly interpreted by the WTS as not literal)
So it was that the beggar died, and was carried by the angels to Abraham’s bosom. The rich man also died and was buried. And being in torments in Hades, he lifted up his eyes and saw Abraham afar off, and Lazarus in his bosom.
“Then he cried and said, ‘Father Abraham, have mercy on me, and send Lazarus that he may dip the tip of his finger in water and cool my tongue; for I am tormented in this flame.’ But Abraham said, ‘Son, remember that in your lifetime you received your good things, and likewise Lazarus evil things; but now he is comforted and you are tormented. And besides all this, between us and you there is a great gulf fixed, so that those who want to pass from here to you cannot, nor can those from there pass to us.’
“Then he said, ‘I beg you therefore, father, that you would send him to my father’s house, for I have five brothers, that he may testify to them, lest they also come to this place of torment.’ Abraham said to him, ‘They have Moses and the prophets; let them hear them.’ And he said, ‘No, father Abraham; but if one goes to them from the dead, they will repent.’ But he said to him, ‘If they do not hear Moses and the prophets, neither will they be persuaded though one rise from the dead.’ ” ~Luke 16:22-31
The grave/ Sheol and Hades
The grave (sheol (Hebrew), hades (Greek for sheol)) is not hell. Hell is the place of the future punishment call “Gehenna” or “Gehenna of fire”. This was originally the valley of Hinnom, south of Jerusalem, where the filth and dead animals of the city were cast out and burned; a fit symbol of the wicked and their future destruction. In the period of the divided monarchy, this valley was the site of a pagan altar, or “high place” (see Deut. 12:2), known as Tophet (“fireplace”). Parents sacrificed their children there to the god Molech. The Bible singles out Ahaz and Manasseh, kings of Judah, as having led the way in this grotesque ritual (2 Chr 28:3; 33:6). But Scripture praises King Josiah for destroying this idolatrous altar during his reforms (2 Kg 23:10). The Valley of Hinnom would become a cemetery known as the Valley of Slaughter (Jer 7:31–32; 19:1–6; 32:35). In time, the valley became so noxious that its name became a synonym for hell. The Hebrew phrase ge (“valley of”) hinnom eventually became the Greek Gehenna (Matt 5:22; Mark 9:43, 45, 47).
Hades is the region of departed spirits of the lost and also included the “blessed” dead in periods preceding the ascension of Christ. So it (the grave) consisted of two compartments, or states: torment for the wicked, and paradise for the righteous (Luke 16:23-31 the parable of Lazarus and the rich man).
The thief on the cross was with Jesus "that day" in paradise (Abraham's Bosom). Now with Christ ascended to heaven, we go to be with Him.
We are confident, yes, well pleased rather to be absent from the body and to be present with the Lord. ~2 Cor 5:8
But if I live on in the flesh, this will mean fruit from my labor; yet what I shall choose I cannot tell. For I am hard-pressed between the two, having a desire to depart and be with Christ, which is far better. ~Phil 1:22,23